Systems and methods for tissue retraction

ABSTRACT

A system for interchangeable retractor blades includes a shell, a first retractor blade, and a second retractor blade. The shell includes a rigid proximal end configured to attach to a surgical retractor and an opening, a distal closed end, and a pliable portion including a pocket in communication with the opening and extending along a length of the shell to the distal closed end. The first retractor blade includes a first geometry received through the opening into the pocket and that shapes the pliable portion to configure the shell in a first configuration. The second retractor blade includes a second geometry received through the opening into the pocket and that shapes the pliable portion to configure the shell in a second configuration.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationSer. No. 61/812,912 entitled “Systems and Methods for Tissue Retraction”which was filed on Apr. 17, 2013 and is incorporated herein by referencein its entirety.

FIELD

The present disclosure generally relates to the field of spinalorthopedics, and more particularly to systems and method for retractingsoft tissue of a surgical area.

BACKGROUND

The spine is a flexible column formed of a plurality of bones calledvertebrae. The vertebrae are hollow and piled one upon the other,forming a strong hollow column for support of the cranium and trunk. Thehollow core of the spine houses and protects the nerves of the spinalcord. The different vertebrae are connected to one another by means ofarticular processes and intervertebral, fibrocartilaginous bodies.Various spinal disorders may cause the spine to become misaligned,curved, and/or twisted or result in fractured and/or compressedvertebrae. It is often necessary to surgically correct these spinaldisorders.

The spine includes seven cervical (neck) vertebrae, twelve thoracic(chest) vertebrae, five lumbar (lower back) vertebrae, and the fusedvertebrae in the sacrum and coccyx that help to form the hip region.While the shapes of individual vertebrae differ among these regions,each is essentially a short hollow shaft containing the bundle of nervesknown as the spinal cord. Individual nerves, such as those carryingmessages to the arms or legs, enter and exit the spinal cord throughgaps between vertebrae.

The spinal disks act as shock absorbers, cushioning the spine, andpreventing individual bones from contacting each other. Disks also helpto hold the vertebrae together. The weight of the upper body istransferred through the spine to the hips and the legs. The spine isheld upright through the work of the back muscles, which are attached tothe vertebrae. While the normal spine has no side-to-side curve, it doeshave a series of front-to-back curves, giving it a gentle “S” shape. Ifthe proper shaping, alignment, and/or curvature are not present due toscoliosis, neuromuscular disease, degenerative discs, tumors, trauma, orother disorder, it may be necessary to straighten or adjust the spineinto a proper alignment and/or curvature.

Generally the correct curvature is obtained by manipulating thevertebrae into their proper position and securing that position withinterbody spacers and a rigid system of screws and rods. In someinstances, plates may secure the construct. Soft tissue retractorsystems are used to provide direct access to the intervertebral spacefor disc extraction and interbody deliver. Generally, direct lateralapproaches include insertion of a retractor system with three or morerobust blades to split the psoas muscle and expand the retractor to pullaway soft tissue from the surgical area to enable access by the surgeon.

One issue during expansion of the retractor is soft tissue encroachmentbetween the opened blades. Other issues may relate to the ease withwhich the retractor expands the surgical area, especially in lateralsurgeries where torque forces acting on distal ends of the blades may besignificant. Complicated retractors lead to longer cleaning andsterilization times.

SUMMARY

A system for interchangeable retractor blades includes a shell, a firstretractor blade, and a second retractor blade. The shell includes arigid proximal end configured to attach to a surgical retractor and anopening, a distal closed end, and a pliable portion including a pocketin communication with the opening and extending along a length of theshell to the distal closed end. The first retractor blade includes afirst geometry received through the opening into the pocket and thatshapes the pliable portion to configure the shell in a firstconfiguration. The second retractor blade includes a second geometryreceived through the opening into the pocket and that shapes the pliableportion to configure the shell in a second configuration.

In other features, the first geometry includes a first radius curvaturein a plane normal to the length of the shell. The second geometryincludes a second radius of curvature in the plane normal to the lengthof the shell that is greater than the first radius of curvature. Thefirst retractor blade includes length commensurate with the length ofthe shell, overall thickness configured to slidably engage with thepocket, and a curved profile commensurate with a curvature of the shellin a plane normal to the length. The second retractor blade includeslength commensurate with the length of the shell, overall thicknessconfigured to slidably engage with the pocket, and a straight profileconfigured to decrease the curvature of the shell in the plane normal tothe length.

A system for retracting tissue from a surgical area includes aretractor, a plurality of shells, a first plurality of blades, and asecond plurality of blades. The retractor includes an actuator thatpositions a plurality of armatures. Each of the plurality of shellsincludes a rigid proximal end attached to each of the plurality ofarmatures and an opening, a distal closed end, and a pliable portionincluding a pocket in communication with the opening and extending alonga length of the shell to the distal closed end. Each of the firstplurality of retractor blades includes a first geometry received throughthe opening into the pocket and that shapes the pliable portion toconfigure the shells in a first configuration. Each of the secondplurality of retractor blades includes a second geometry receivedthrough the opening into the pocket and that shapes the pliable portionto configure the shells in a second configuration.

In other features, the first geometry includes a first radius curvaturein a plane normal to the length of the shell and the secondconfiguration includes a second radius of curvature in the plane normalto the length of the shell that is greater than the first radius ofcurvature. The shells receive the first plurality of blades and theactuator positions the shells in a first position enclosing a firstviewing area with a circular area of a first diameter.

In other features, the actuator positions the shells to a secondposition forming a second viewing area encompassed by the shells andplanes extending from edges of adjacent shells, the second viewing areagreater than the first viewing area. In still other features, the secondviewing area includes a triangular area having rounded vertices with thefirst radius of curvature.

In other features, the shells receive the second plurality of blades andthe actuator maintains the shells in the first position enclosing athird viewing area with a triangular area that is greater than the firstviewing area.

In other features, the actuator positions the shells to a secondposition forming a fourth viewing area encompassed by the shells andplanes extending from edges of adjacent shells, the fourth viewing areagreater than the third viewing area. In still other features, the fourthviewing area includes a triangular area having rounded vertices with thesecond radius of curvature.

In other features, each proximal end of the shells includes a taperedportion to ease insertion over a dilator into surrounding tissue. Instill other features, at least one of the first plurality of blades andthe second plurality of blades includes decreasing radius of curvatureat one edge to for nesting with adjacent blades.

A method for retracting tissue from a surgical area includes the stepsof attaching a plurality of shells to a retractor, each of the pluralityof shells having a rigid proximal end attached to each of the pluralityof armatures and an opening, a distal closed end, and a pliable portionincluding a pocket in communication with the opening and extending alonga length of the shell to the distal closed end; inserting a firstplurality of retractor blades into the plurality of shells, eachincluding a first geometry, each received through the opening into thepocket and shaping the pliable portion to configure the shells in afirst configuration; and inserting a second plurality of retractorblades into the plurality of shells, each including a second geometry,each received through the opening into the pocket and shaping thepliable portion to configure the shells in a second configuration.

In other features, the first geometry includes a first radius ofcurvature in a plane normal to the length of the shell and the secondconfiguration includes a second radius of curvature in the plane normalto the length of the shell that is greater than the first radius ofcurvature.

In other features, the method includes the step of removing at least oneof the first plurality of blades before inserting one of the secondplurality of blades. In still other features, the method includes thestep of positioning the plurality of shells while in the firstconfiguration to a first position and inserting the plurality of shellsover a dilator. In yet other features, the method includes the step ofpositioning the plurality of shells while in the second configuration toa second position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective bottom view of an exemplary retractor for usewith the systems and methods of tissue retraction according to theprinciples of the present disclosure.

FIG. 2 is a perspective top view of the retractor of FIG. 1 according tothe principles of the present disclosure.

FIG. 3 is a perspective view of the back of the retractor of FIG. 1according to the principles of the present disclosure.

FIG. 4 is a flowchart of methods according to the principles of thepresent disclosure.

FIGS. 5A-5C are perspective views of various components of the systemaccording to the principles of the present disclosure.

FIGS. 6A-6D are a series of perspective views illustrating systems andmethods according to the principles of the present disclosure.

FIGS. 7A-7D are a series of perspective views illustrating systems andmethods according to the principles of the present disclosure.

FIGS. 8A-8C are a series of side views illustrating systems and methodsaccording to the principles of the present disclosure.

FIGS. 9A and 9B are distal views of the system in a first configurationof the present disclosure in an insertion position and a retractedposition.

FIGS. 10A and 10B are distal views of the system in a secondconfiguration of the present disclosure in an insertion position and aretracted position.

FIG. 11 is a distal view illustrating the difference in size of surgicalviewing areas of the system in the first configuration and secondconfiguration when in the retracted positions.

DETAILED DESCRIPTION

Soft tissue retractor systems are used in minimally invasive spinefusion cases to provide direct access to the intervertebral space fordisc extraction and interbody deliver. Generally, direct lateralapproaches include insertion of a retractor system with three or morerobust blades to split the psoas muscle and expand the retractor to pullaway soft tissue from the surgical area to enable access by the surgeon.One issue during expansion of the retractor is soft tissue encroachmentbetween the opened blades. This soft tissue reduces the field of viewand may impede passage of instrumentation. Ideally, increasing the widthof the blades reduces tissue encroachment. However, the width of theblades is limited by the need to nest the collapsed blade segmentscircumferentially around a dilator, typically in a cylindricalconfiguration. The blades must create a smooth exterior that can passover the dilator and through the soft tissue with minimal effort.

To overcome the soft tissue encroachment, auxiliary blades and shims maybe attached to the retractor and/or blades to fill some of the gapsbetween the blades. This increases the complexity and length of theprocedure. Therefore, a means of increasing the blade width to improvesoft tissue extraction is desirable to reduce the need for usingauxiliary devices to supplement the retractor blades.

Embodiments of the invention will now be described with reference to theFigures, wherein like numerals reflect like elements throughout. Theterminology used in the description presented herein is not intended tobe interpreted in any limited or restrictive way, simply because it isbeing utilized in conjunction with detailed description of certainspecific embodiments of the invention. Furthermore, embodiments of theinvention may include several novel features, no single one of which issolely responsible for its desirable attributes or which is essential topracticing the invention described herein. The words proximal and distalare applied herein to denote specific ends of components of theinstrument described herein. A proximal end refers to the end of aninstrument nearer to an operator of the instrument when the instrumentis being used. A distal end refers to the end of a component furtherfrom the operator and extending towards the surgical area of a patientand/or the implant.

FIG. 1 is a perspective, cross-sectional bottom view of a retractordevice 100 which includes a housing 102, a handle assembly 120, threeblade holders 104 (a, b, c), and three blades 108 (a, b, c). As can beunderstood by one skilled in the art, there can be any number of bladeholders 104 and blades 108.

The housing 102 further includes a hollow interior or a halo 110 formedby the sides 105(a, b). The sides 105 (a, b) are joined together at thehandle assembly 120 and form a gap 111 opposite the handle assembly 120.As can be understood by one skilled in the art, the sides 105 can bejoined together at all times and not form any gaps. The hollow interior110 further includes a center 112 that is located substantially in thecenter of the hollow interior 110.

As shown in FIG. 1, the blade holders 104 are configured to be slidablycoupled to the housing 102, which allows the blade holders 104 to becapable of translational movement within the same plane as the plane ofthe housing 102. The movement of the blade holders 104 is configured tobe within the hollow interior 110 and to and/or from (or away from) thecenter 112 (i.e., radially). The housing 102 further includes channels142 (a, b, c) that are configured to hold the blade holders 104 andallow such translational movement of the blade holders 104. The channels142 are further configured to be aligned in a direction of the center112, thereby allowing blade holders 104's translational movement.

The handle assembly includes a permanent handle 124 and an actuatinghandle 122. The permanent handle 124 may be rigidly coupled to thehousing 102. In one embodiment, the permanent handle 124 may bepermanently coupled to the sides 105. The actuating handle 122 ispivotally coupled to a spool mechanism 126, which, in turn, may becoupled to the sides 105 and/or to the permanent handle 124. The spoolmechanism 126 is configured to allow actuating handle 122 to at leastpartially pivot to and from the permanent handle 124. The handleassembly 120 is further configured to be coupled to a plurality of cablesystems 131(a, b, c). The spool mechanism 126 can be a catch-and-releasemechanism (e.g., ratchet type) that is configured to pull cables whenthe mechanism is actuated by a handle and release cables when the handleis released. This mechanism may include a spring-loaded device and astopper device that allow pulling and releasing of the cables. As can beunderstood by one skilled in the art, other mechanisms and methods ofpulling/tensioning and releasing the cables may be used.

The cable system 131 a is configured to connect the handle assembly 120and the first blade holder 104 a. The cable system 131 b is configuredto connect the handle assembly 120 and the second blade holder 104 b.The cable system 131 c is configured to connect the handle assembly 120and the third blade holder 104 c.

The cable system 131 a further includes a cable 132 a and a plurality ofpins 133 (a, b, c, d, e). The cable 132 a is configured to bepermanently secured to the pin 133 a on the housing 105 a as well as tobe permanently secured to the spool mechanism 126 of the handle assembly120. The cable 132 a forms a sliding or a rolling connection with otherpins 133 (b, c, d, e), including the pin 133 b located on the bladeholder 104 a. The pins 133 a, 133 b, and 133 c form a triangularcomposition that allows translational movement of the blade holder 104a. The pins 133 d, 133 e allow the cable 132 a to be strung around theside 105 a so as to prevent interference of the cable 132 a with othercomponents of the retractor device 100 as well as patient's body tissuewhich is selected for retraction.

The cable system 131 b may further include a cable 132 b and a pluralityof pins 135 (a, b, c, d, e). The cable 132 b is configured to bepermanently secured to the pin 135 a on the housing 105 b as well as tobe permanently secured to the spool mechanism 126 of the handle assembly120. The cable 132 b forms a sliding or a rolling connection with otherpins 135 (b, c, d, e), including the pin 135 b located on the bladeholder 104 b. The pins 135 a, 135 b, and 135 c form a triangularcomposition that allows translational movement of the blade holder 104b. The pins 135 d, 135 e allow the cable 132 b to be strung around theside 105 b so as to prevent interference of the cable 132 b with othercomponents of the retractor device 100 as well as patient's body tissuewhich is selected for retraction.

The cable system 131 c further includes a cable 132 c and pins 137(a,b). The cable 132 c may be configured to be permanently secured to thepin 137 a on the housing 105 a as well as to be permanently secured tothe spool mechanism 126 of the handle assembly 120. The cable 132 cforms a sliding or a rolling connection with pin 137 b located on theblade holder 104 c. The pins 137 a and 137 b form an angular compositionthat allows translational movement of the blade holder 104 c. The pins137 a and 137 b allow the cable 132 c to be strung around the side 105 aso as to prevent interference of the cable 132 c with other componentsof the retractor device 100 as well as patient's body tissue which isselected for retraction.

As stated above, the cable systems 131 may be configured to allowtranslational movement of the blade holders 104, i.e., movement to andfrom the center 112 of the hollow interior 110. The blade holders 104may be configured to be disposed within the housing in a triangularfashion. As can be understood by one skilled in the art, the bladeholders 104 can be disposed in any other fashion, corresponding to thenumber and position of the blade holders used. To translate the bladeholders 104 away from the center 112, the actuating handle 122 is forcedtowards the permanent handle 124 of the handle assembly 120 (i.e.,squeezed). This causes cable systems 131 to tension and pull the cables132 towards the spool mechanism 126. Once cable 132 a is pulled, thetriangular arrangement of pins 133 (a, b, c) forces the blade holder 104a to pull away radially from the center 112. Similarly, once the cable132 b is pulled, the triangular arrangement of pins 135(a, b, c) forcesthe blade holder 104 b to radially pull away from the center 112. Also,once the cable 132 c is pulled, the angular arrangement of pins 137(a,b) forces the blade holder 104 c to radially pull away from the center112. As can be understood by one skilled in the art, the pulling of eachblade holder 104 can be simultaneous or selective (preferably,simultaneous). Further, the blade holders 104 can be pulled from thecenter 112 all the way to the sides 105 either in one application offorcing the handle 122 to the handle 124 or in several applications(i.e., gradually). The releasing of the blade holders 104 can be done ina similar fashion, but in a reverse order, i.e., releasing the handle122 to release blade holders 104.

Blade holders 104(a, b, c)—which may also be referred to herein asarmatures—may further include blade holder tips 106(a, b, c),respectively. Blade holder tips 106 are configured to couple the bladeholders 104 to the blades 108. Thus, the blade holder tip 106 a couplesthe blade holder 104 a to the blade 108 a; the blade holder tip 106 bcouples the blade holder 104 b to the blade 108 b; and the blade holdertip 106 c couples the blade holder 104 c to the blade 108 c. In oneembodiment, the blade holder tips 106 may be configured to receiveblades 108 and secure the blades 108 inside the tips 106. The bladeholder tips are further configured to allow doctors (or other qualifiedprofessionals) to exchange one set of blades 108 for another, if suchexchange is desired. The blades 108 and the tips 106 can be frictionallyfit together or a locking mechanism can be used to secure the blades 108and the tips 106. In an alternate embodiment, the tips 106 and/or bladeholders 104 can also be interchangeable, as desired.

As shown in FIG. 1, once the blade holders 104 are released, the blades108 are pushed together towards the center 112. In the illustratedembodiments, the combination of the three released blades 108 forms acircle. As can be understood by one skilled in the art, the combinationof the released blades can form any other shape, such as square,rectangle, polygon, oval, or any other regular or irregular shape. Ascan be further understood by one skilled in the art, there can be anynumber of blade holders 104, blade holder tips 106, and blades 108coupled to the housing. The blades 108 along with corresponding holdingmechanisms may be added or removed as desired. Also, the blades 108 canhave any size shape, thickness, material or have any other parameters.

Referring to FIGS. 2-3, the blades 108 can have any length, width, orshape. Specifically, FIG. 2, which is a top perspective view of theretractor 100, illustrates that the combination of released blades 108forms a hexagon-shaped cylinder. Alternatively, FIG. 3, which is abottom perspective view of the retractor 100, illustrates that thecombination of released blades 108 forms a regular cylinder. As furtherillustrated in FIGS. 1-3, the sides 105(a, b) can be multi-layered,thereby allowing placement of cable systems 131 between the layers. Thisprevents interferences of the cable systems 131 during application ofthe retractor device 100 on the patient.

FIG. 4 illustrates a method 400 for retracting a body tissue within abody of a patient using a retractor device 100, illustrated in FIGS.1-3. In step 402, the retractor blades 108 are released to allow theblades 108 to be pushed together towards the center 112 of the hollowcenter portion 110. In one embodiment, the step 402 is performed if theblades 108 are in a tensioned state, i.e., pulled away from the center112.

In step 404, the retractor device 100, having blades 108 pushed togethertowards the center 112, is placed on the patient at a location wherebodily tissue needs to be retracted. This location can be any locationon or within the body, such as a location where a surgical procedure isbeing or will be performed. In an embodiment, the retractor device canbe used to expose spinal structures during spinal surgery. This allowsfor minimal disruption of spinal muscles and sensitive elements of theposterior, lateral, and anterior regions of the spine. The retractordevice 100 can also be used in the thoracolumbar region, as well as,sacral and cervical regions of the spine, or any other regions.

In step 406, the handle assembly 120 is used to tension the cables 132of the cable systems 131. This may be accomplished be forcing thepermanent handle 124 and the actuator handle 122 together (i.e.,squeezing them together). Once the cables 132 are tensioned, the bladeholders 104 slide or translate along the channels 142 away from thecenter 112 of the hollow portion 110. Once the blade holders 104 beginto slide, the blades 108 begin moving away from the center 112 as welland engage bodily tissue coming in contact with the blades 108. Byforcing the blades 108 apart, the engaged bodily tissue are alsospread/forced apart, as illustrated in step 408. As stated above, thisexposes the bodily regions on which a surgical procedure may beperformed. Also, by spreading the tissue apart, the surgeon (or otherqualified professional) can easily move in and out any surgical toolsneeded for performing the surgical procedure.

As can be understood by one skilled in the art, the retractor device 100and/or any of its components may have any size, shape, length,thickness, height, weight, or any other parameters. Such parameters maybe selected by the surgeon (or other qualified professional) forperformance of specific procedures. Further, the retractor device 100and/or any of its components may be manufactured from metal, plastic,synthetic material, or other suitable materials, or any combinationthereof.

Referring now to FIGS. 5-12, an exemplary system 200 for use with aretractor, such as retractor 100, includes features that enableinsertion over a traditional dilator assembly and retractopm of softtissue. The system 200 includes several components including shells 210that receive retractor blades of various shapes. The shells 210 mayinclude flexible or pliable portions. For example, the shells 210 maycomprise various biocompatible plastics, braided mesh, or other materialcapable of altering shape to conform to various shaped blades. Theshells 210 may be referred to as jackets, sleeves, or blade receptacles.In some examples, the blades of the present disclosure include a firstplurality of blades 220 and second plurality of blades 230. The firstblades 220 may include a first radius of curvature in the plane normalto the length of the blades. The second blades 230 may include a secondradius of curvature in the plane normal to the length of the blades thatis greater than the first radius. Alternately, one or more of the firstblades 220 and the second blades 230 may include widths.

The shell 210 may be used in conjunction with the first blades 220 toinsert the system 200 over a curved dilator, such as a cylindrical tubedilator. Once inserted, the first blades 220 may be removed and secondblades 230 subsequently inserted. The second blades 230 may increase thediameter or area of the opening created by the retractor 100 over thefirst blades 220 by improving tissue retraction and preventing tissueencroachment into the surgical viewing area. The system 200 may includetwo or more of each component (shell, first blade, and second blade) asdescribed herein. For ease of discussion, one of each of the componentsis described with reference to FIGS. 5A-5C.

Referring now to FIG. 5A, the shell 210 includes a substantially slenderprofile extending a length L from a proximal end 211 to a distal end219. Near the proximal end 211, a mount 212 for attachment to aretractor may include one or more attachment features and/or geometricfeatures for removable coupling with the retractor. The mount 212 mayinclude a boss 213 on the proximal end 211. The proximal end 211 may bemore rigid than the distal end 219 to provide a strong connection withthe retractor 100. The proximal end 211 further includes aproximal-facing opening 214 for receiving the various-shaped bladesincluding the first blades 220 and second blades 230. The opening 214may communicate with an interior pocket 215 extending within ablade-receiving portion 216 of the shell 210 to the distal end 219. Thepocket 215 may bend, flex, expand, and conform to any of the blades 220and 230. The distal end 219 may include a tapered portion 217 to easeinsertion of the shell 210 over a dilator and into surrounding tissue.The distal end 219 may be closed. The shell 210 may include translucenttips 218 within the tapered portion 217 or along the length of the shell210. The shell 210 may include various other pathway and/or connectionsfor connecting instrumentation including probes, stimulators, andlighting.

Referring now to FIG. 5B, the first blade 220 includes a substantiallyslender profile extending approximately length L from a proximal end 221to a distal end 229. The proximal end 221 may include a tab 222 forinserting and removing the first blade 220 from the pocket 215. Thefirst blade 220 may include various radii of curvature in a plane normalto the length L. The curvature may be substantially uniform or includedecreasing or increasing radius at either end 221, 229 to enable nestingof multiple first blades 220 as describe herein. For example, near themiddle of first blade edge 223, the radius may be R1 and near the end ofthe curved edge 223, the radius may be R. R1 may be greater than R. Thecurvature may be substantially uniform through a mid-portion 226 of thefirst blade 220. The first blade 220 may be substantially rigid andcomposed of hard plastic, metal, or other materials suitable forsurgical use and capable of providing structure to the shell 210. Thefirst blade 220 may include a tapered portion 227 near the distal end229 to ease insertion into the pocket 215 of the shell 210. The firstblade 220 may include various channels and pathways for instrumentationincluding probes, stimulators, and lighting.

Referring now to FIG. 5C, the second blade 230 includes a substantiallyslender profile extending approximately length L form a proximal end 231to a distal end 239. The proximal end 231 may include a tab 232 forinserting and removing the second blade 230 from the pocket 215. Thesecond blade 230 may include a substantially flat profile with a radiusof curvature R2 substantially greater than the radius of curvature R1 ofthe first blade 220. In some examples, the second radius of curvature R2may be infinite as in the case of a flat, straight blade. The secondblade 230, thus may include a width W. The curvature may besubstantially uniform or include decreasing or increasing radius toenable nesting of multiple second blades 230 as describe above withrespect to the first blade 220. The curvature may be substantiallyuniform through a mid-portion 236 of the second blade 230. The secondblade 230 may be substantially rigid and composed of hard plastic,metal, or other materials suitable for surgical use. The second blade230 may include a tapered portion 237 near the distal end 239 to easeinsertion into the pocket 215 of the shell 210. The second blade 230 mayinclude various channels and pathways for instrumentation includingprobes, stimulators, and lighting.

Referring now to FIGS. 6A-6D and 7A-7D, multiple shells 210, firstblades 220, and second blades 230 may be used to insert the system 200in a minimally invasive surgery (MIS) procedure. The system 200 may beused with one or more cylindrical dilators (not shown) that are firstinserted into a patient to create a MIS pathway. For example, a seriesof increasing diameter dilators may be inserted into a patient as isknown in the art until a final dilator remains. They system 200 may becoupled with the retractor 100 to position the shells 210.

In FIG. 6A, three shells 210 a, 210 b, and 210 c (collectively shells210) are assembled together (such as through attachment to a retractor)in a circular pattern to form generally system 200 with a proximal end201 and a distal end 209. The proximal end 201 of the system 200 may beinserted over a final dilator. For example, the final dilator mayinclude a diameter slightly less than or substantially equal to adiameter D of an opening 202 formed by the shells 210 of the tubularsystem 200. The opening 202 may be substantially circular at theproximal end 201 and extend the length L of the shells 210 to the distalend 209. At the distal end 209, the opening 202 may decrease slightly.

In FIG. 6B, three first blades 220 a, 220 b, and 220 c (collectivelyfirst blades 220) may be inserted into respective shells 210 a, 210 b,and 210 c of the system 200 to provide strength and rigidity forinsertion over the final dilator. Each of the first blades 220 may beinserted into respective proximal facing openings 214 a, 214 b, and 214c. Continuing with FIG. 6C, the first blades 220 may be advanceddistally into the respective pockets 215 a, 215 b, and 215 c (none ofwhich are shown) of the shells 210. As the first blades 220 advance, theblade receiving portions 216 a, 216 b, and 216 c (not shown) of theshells 210 become more rigid to conform to the shape of the first blades220. In FIG. 6D, the first blades 220 have completely advanced into thedistal ends 219 of the shells 210 to form a substantially rigid tubularsystem 200 with rigid opening 202 extending from the proximal end 201 tothe distal end 209.

In FIG. 7A, the rigid tubular system 200 has been inserted over thefinal dilator using the first blades 220. Each of the first blades 220has been removed. The final dilator may be removed or left within theopening 202. The three shells 210 a, 210 b, and 210 c may remaintogether in a circular pattern to form generally a tubular system 200with the proximal end 201 and the distal end 209. For example, uponremoval of the first blades 220, each of the shells 210 may becomepliable again. In some examples, each of the first blades 220 may beremoved one at a time and subsequently replaced one at a time by each ofthe second blades 230. In this manner, the system 200 may becomepartially pliable and partially rigid until all first blades 220 havebeen swapped out for second blades 230.

In FIG. 7A, three second blades 230 a, 230 b, and 230 c (collectivelysecond blades 230) may be inserted into respective shells 210 of thesystem 200 to provide strength and rigidity for retraction of tissue andimproved prevention of encroachment of tissue. Each of the second blades230 may be inserted into respective proximal facing openings 214 a, 214b, and 214 c. Continuing with FIG. 7B, the second blades 230 may beadvanced distally into the respective pockets 215 a, 215 b, and 215 c(none shown) of the shells 210. As the second blades 230 advance, theblade receiving portions 216 a, 216 b, and 216 c (not shown) of theshells 210 become more rigid to conform to the shape of the secondblades 230. In FIG. 7C, the second blades 230 have completely advancedinto the distal ends 219 of the shells 210 to form a substantially rigidtriangular system 200 with a triangular opening 202 extending from theproximal end 201 to the distal end 209. Referring now to FIG. 7D, thetriangular opening 202 may be retracted using a retractor instrumentsuch as the instrument 100 described herein. Any suitable instrumentwith the ability to position each shell 210 relative to one another maybe used to retract the tissue.

FIGS. 8A-8C illustrate exemplary steps of a method of using a retractorinstrument 100, dilators 300, and system 200 of the present disclosure.In FIG. 8A, a patient may be positioned such that the side of the bodyis facing the surgeon. The surgeon may make an incision into the body tobegin to access the spinal column and intervertebral disc space betweentwo adjacent vertebrae. As shown in FIGS. 8A-8C, the surgeon may accessa lumbar region of the spinal column. The surgeon may insert a series ofconcentric dilators as is known generally in the art of minimallyinvasive surgery (MIS) procedures until a final dilator 300 has beeninserted. The retractor instrument 100 may be positioned over a proximalend 301 of the dilator 300 to receive the system 200 as describedherein.

In FIG. 8B, the system 200 has been inserted over the dilator 300 usingthe first blades 220. The first blades 220 reinforce the pliableportions of the shells 210 of the system 200 as the shells 210 advancedistally into the tissue of the patient. Once the shells 210 haveadvanced far enough into the tissue, the mounts 212 of the shells 210may be attached to various armatures and mounting brackets of theinstrument 100 to retain the generally tubular shape of the opening 202at the proximal end 201 of the system 200. The dilator 300 may beremoved or may remain in the tissue. Subsequently, the second blades 230may be inserted into the shells 210 to form the triangular system 200.In FIG. 8C, the triangular system 200 may be used to retract tissue andcreate a wider opening than can be obtained using the first blades 220as shown below with respect to FIGS. 9A-11.

FIGS. 9A-11 provide several views looking into the distal end of thesystem 200 with first blades 220 and second blades 230 inserted into theshells 210. For example, in FIG. 9A, the first blades 220 have beeninserted into the shells 210 of the system 200. The first blades 220within the shells 210 cause the system 200 to become more rigid as shownin FIGS. 6A-6D. The shells 210 form the generally rigid circular opening202 extending from the proximal end 201 to the distal end 209. Theopening 202 may include diameter D1 with a first viewing area A1. Thefirst viewing area A1 may be substantially a circular area.

The system 200 may be used to retract tissue using the first blades 220as shown in FIG. 9B. As the shells 210 with the first blades 220 spreadapart, the opening 202 increases in size to a second viewing area A2.The second viewing area A2 may include a substantially triangular areawith curved vertices (due to the radius of curvature R1 of the firstblades 220) formed by the shells 210 and imaginary planes extending fromadjacent edges 250 of the shells 210 as represented by dotted lines. Inpractice, soft tissue may encroach past the imaginary planes somewhat.

However, the second viewing area A2 may be increased by using the secondblades 230 in place of the first blades 220. For example, the firstblades 220 may be removed after insertion over the final dilator asdescribed above. The second blades 230 may then be inserted into theshells 210.

In FIG. 10A, the second blades 230 have been inserted into the shells210 of the system 200 after removal of the first blades 220. The secondblades 230 within the shells 210 cause the system 200 to become morerigid as shown in FIGS. 7A-7D. The shells 210 form the generallytriangular opening 202 extending from the proximal end 201 to the distalend 209. The opening 202 may include three sides of width Wcorresponding to the shells 210 that form a generally triangular thirdviewing area A3. The third viewing area A3 may be greater than the firstviewing area A1.

The system 200 may then be used to retract tissue using the secondblades 230 as shown in FIG. 10B. As the shells 210 with the secondblades 230 spread apart, the opening 202 increases in size to a fourthviewing area A4 that is substantially greater than the second viewingarea A2 formed using the first blades 220. Like the second and thirdviewing areas A2 and A3, the fourth viewing area A4 may include asubstantially triangular area with flattened vertices having width W(due to the radius of curvature R2 or width W of the second blades 220)formed by the shells 210 and planes extending from the adjacent edges250 of the shells 210 as represented by the dotted lines.

As shown in FIG. 11, the second blades 230 provide a greater area ofretraction than using the first blades 220. Shaded areas represent theadditional area retracted using the second blades 230 over the firstblades 220.

Example embodiments of the methods and systems of the present inventionhave been described herein. As noted elsewhere, these exampleembodiments have been described for illustrative purposes only, and arenot limiting. Other embodiments are possible and are covered by theinvention. Such embodiments will be apparent to persons skilled in therelevant art(s) based on the teachings contained herein. Thus, thebreadth and scope of the present invention should not be limited by anyof the above-described exemplary embodiments, but should be defined onlyin accordance with the following claims and their equivalents.

The invention claimed is:
 1. A system for interchangeable retractorblades, comprising: a shell having a rigid proximal end configured toattach to a surgical retractor and an opening, a distal closed end, anda pliable portion including a pocket in communication with the openingand extending along a length of the shell to the distal closed end; afirst retractor blade including a first geometry received through theopening into the pocket and that shapes the pliable portion to configurethe shell in a first configuration; and a second retractor bladeincluding a second geometry received through the opening into the pocketand that shapes the pliable portion to configure the shell in a secondconfiguration.
 2. The system of claim 1, wherein the first geometryincludes a first radius curvature in a plane normal to the length of theshell.
 3. The system of claim 2, wherein the second configurationincludes a second radius of curvature in the plane normal to the lengthof the shell that is greater than the first radius of curvature.
 4. Thesystem of claim 1, wherein the first retractor blade includes lengthcommensurate with the length of the shell, overall thickness configuredto slidably engage with the pocket, and a curved profile commensuratewith a curvature of the shell in a plane normal to the length.
 5. Thesystem of claim 4, wherein the second retractor blade includes lengthcommensurate with the length of the shell, overall thickness configuredto slidably engage with the pocket, and a straight profile configured todecrease the curvature of the shell in the plane normal to the length.6. A system for retracting tissue from a surgical area, comprising: aretractor including an actuator that positions a plurality of armatures;a plurality of shells each having a rigid proximal end attached to eachof the plurality of armatures and an opening, a distal closed end, and apliable portion including a pocket in communication with the opening andextending along a length of the shell to the distal closed end; a firstplurality of retractor blades, each including a first geometry receivedthrough the opening into the pocket and that shapes the pliable portionto configure the shells in a first configuration; and a second pluralityof retractor blades, each including a second geometry received throughthe opening into the pocket and that shapes the pliable portion toconfigure the shells in a second configuration.
 7. The system of claim6, wherein the first geometry includes a first radius curvature in aplane normal to the length of the shell and the second geometry includesa second radius of curvature in the plane normal to the length of theshell that is greater than the first radius of curvature.
 8. The systemof claim 7, wherein the shells receive the first plurality of blades andthe actuator positions the shells in a first position enclosing a firstviewing area with a circular area of a first diameter.
 9. The system ofclaim 8, wherein the actuator positions the shells to a second positionforming a second viewing area encompassed by the shells and planesextending from edges of adjacent shells, the second viewing area greaterthan the first viewing area.
 10. The system of claim 9, wherein thesecond viewing area includes a triangular area having rounded verticeswith the first radius of curvature.
 11. The system of claim 8, whereinthe shells receive the second plurality of blades and the actuatormaintains the shells in the first position enclosing a third viewingarea with a triangular area that is greater than the first viewing area.12. The system of claim 11, wherein the actuator positions the shells toa second position forming a fourth viewing area encompassed by theshells and planes extending from edges of adjacent shells, the fourthviewing area greater than the third viewing area.
 13. The system ofclaim 12, wherein the fourth viewing area includes a triangular areahaving rounded vertices with the second radius of curvature.
 14. Thesystem of claim 11, wherein each proximal end of the shells includes atapered portion to ease insertion over a dilator into surroundingtissue.
 15. The system of claim 11, wherein at least one of the firstplurality of blades and the second plurality of blades includesdecreasing radius of curvature at one edge to for nesting with adjacentblades.
 16. A method for retracting tissue from a surgical area,comprising: attaching a plurality of shells to a retractor, each of theplurality of shells having a rigid proximal end attached to each of aplurality of armatures on the retractor and an opening, a distal closedend, and a pliable portion including a pocket in communication with theopening and extending along a length of the shell to the distal closedend; inserting a first plurality of retractor blades into the pluralityof shells, each including a first geometry, each received through theopening into the pocket and shaping the pliable portion to configure theshells in a first configuration; inserting a second plurality ofretractor blades into the plurality of shells, each including a secondgeometry, each received through the opening into the pocket and shapingthe pliable portion to configure the shells in a second configuration.17. The method of claim 16, wherein the first geometry includes a firstradius curvature in a plane normal to the length of the shell and thesecond configuration includes a second radius of curvature in the planenormal to the length of the shell that is greater than the first radiusof curvature.
 18. The method of claim 17, further comprising the step ofremoving at least one of the first plurality of blades before insertingone of the second plurality of blades.
 19. The method of claim 16,further comprising positioning the plurality of shells while in thefirst configuration to a first position and inserting the plurality ofshells over a dilator.
 20. The method of claim 19, further comprisingpositioning the plurality of shells while in the second configuration toa second position.